Note: Descriptions are shown in the official language in which they were submitted.
CA 02401274 2006-05-15
FLEXIBLE SUPPORT AND METHOD FOR A STEADY BEARING
FIELD OF THE INVENTION
The present invention relates generally to apparatus and methods for
supporting
steady bearings, which are used to support impeller shafts mounted in a
variety of reactors,
vessels and mixing apparatus. Steady bearings for shafts in such vessels are
in wide use in
the chemical, petroleum, pharmaceutical, cosmetic, food preparation and other
industries.
More particularly, the present invention relates to a flexibly supported
steady bearing to
support impeller shafts mounted in a variety of reactors, vessels and mixing
apparatus.
BACKGROUND OF THE INVENTION
When in operation impeller shafts are subject to a number of forces that act
to
damage and possibly lead to failure of the impeller shaft. A mixer shaft
driving an impeller
in a vessel can undergo substantial dynamic bending distortion during mixing
operation.
This deflection can cause permanent damage or distortion and even complete
failure of the
impeller shaft during operation. It is also known that impeller shafts,
especially longer
shafts are prone to lateral displacement while in operation, due to the force
of loads in the
mixing vessel.
It is known to provide one or more intermediate steady bearings along an
impeller
shaft to control dynamic bending distortion of the shaft. In addition, such
assemblies
provide lateral stability to the impeller shaft during operation. Even when an
intermediate
steady bearing is used to support an impeller shaft as indicated above, the
shaft can still be
prone to deflection during operation. In rigid bearing designs it may not be
possible for the
bearing to track the angular changes in the contact surface of the impeller
shaft when the
shaft is subject elastic deflection during operation. This leads to hard
contact of the
impeller shaft at the two ends of the bearing assembly. Hard contact resulting
from this
deficiency in rigid bearing designs can lead to excessive and uneven wear of
bearing
3 0 components, e.g., in an hourglass pattern.
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Accordingly, it i.s des:irable t.o provide a
flexible steady bear ing support <:x:>::err~;l _~r th t a:L lows the
fearing component:: tc:~~ t_:rat;:~; t:lae ~~ .>nt~-cc~t surfac:~.e of the
impeller. shaft where the :..mp~-~ller i~~ ~r~ ope:rat:i.on.
SUMMARY OF THE INVEhITION
It is therefore ;~ fcatu.re and advantage of the
present invention to provide ~an improved flexible support
for a steady bearing in r~ot:~t:Lcorm~l c:~crnt.aet:. with thfe ;surface
of a sha.~ft, whioh allc~w~, tlm ~:.e;~r:i.ric~ t~:ric~ housing to track
the contact surface of an impeller shaft, even when the
shaft is subject to significant elastic angular deflection
during operation..
The above and other feat-~.m°e~; acid advant:.ages are
achieved through the use of a novel flexible support for a
steady bearing usirLc~ a flexible disc pack.
According to thE~ p:r_esear. invention, there is
provided a flexible support assem..hhly for supporting a
steady bearing in rotational contact witch the surf=ace of a
shaf t i.n a vessel , c~ompri s iro.g :
a bearing hous:i.ng ;~_z~.~poi°ti.n~~ t;l-ie ~~tead.y ~ea:ring;
a support ri~.~g suspera.ded f r-carn ~._ he vessel ; and
a f lexi.b.Le di:>c pace f:l e.~ib J._y~ connect ing said
housing t;o said sup,~aort: x i.nc.~ .
Accor_diru~ to l:.h.r- ~~r~.s~:cvi: zr;vf~x~r.:i.c:>r~., tr~E.z:w:. i.s also
provided a flexible support a5semb:iy for supporting a
steady bearing :in ~.~otatic>rla~ c::c>nt:.ac~t~ wi;.r~ ~~he surf-ace of a
s:Yaft in a 'vessel, c~om~::a:~i.~i.r~.~~.~:
a bearing housing ,~~..~~?~~oz°ti:,v.~ the steady bc~arinc~;
a support ring suspended from t.: he vessel; and
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CA 02401274 2003-05-07
a flexible disc pack connecting said housing to
:>aid suyport :ring,
wherein the s~aft :i.:r::,atatable about a
longitudinal a~:is and sa:i.d disc pack flexes t:o permit
angular relative movement between <.i longitudinal axis of
said bearing hou;:~ing and a~ ~ ar~~~~_z.t ud:imal a~: i s of said
support ring,
According to the present i.zzven.tion, there is also
provided a flexible support. assembly for supporting a
steady earing in rotational c:.>ntac:t: w:it~~ the suriac:e
b of a
shaft in a vessel, compr:i.sinrg:
a bearing housing supporting the steady bearing;
a support ring suspended fro~~ the vessels and
a flexible disc tw>~zc~k: i lexi..bl_y connecting
said
housing to said su~:~por~:: z.~in~:~,
wherein said disc pack comprises a first
pluralit y of moun,::ing holes at ,~ first. constant radial
distance fr_orn t:he centeu~ crnff ;:,t:~ici disc ~~ack and
a second
pluralit y of mounting ho3.e~~a at s, r:~ec~c.~nd const.ar~t
radial
distance from the center ot~ said disc pack, and ;paid disc
pack is attached t.o ~;a:i.d bear:i.ry:~ l~c:.~u;~ir~g at
said first
mounting hole; anc:::i sa3..d c::Ja..sr.. ~:~aw~i~ i, attached
to said
support .ring at said second mata.nt~ :i.ric~ holes .
According to the present: ir:ventian, therf.~ is
also
provided a f:lex.ib:Ie ;:7uppcrt~ assearnia:l.y for supp~ort;ing
a
s~eady bearing h;:.mi.tac:~ fi=.st:: a:cn:;; aF~c.c_~z.,.cl
k~e>a.i:ings in
rotation al contact with. the :;z;~x:fruc~= c::.i~ a :hafi~
in ,:~ vessel.,
cornprismg
a fir:~t bear°~rrg l~m~u..i.::,i_rzc:~ ~:~u~~_~c~uriding tine first
bearing;
<,a
CA 02401274 2006-06-27
r
a second bearing housing surrounding the second
bearing;
a support ring suspended from the vessel;
a first flexible disc pack connecting the first
housing to the support ring; and
a second flexible disc pack connecting the second
housing to the support ring.
According to the present invention, there is also
provided a method of supporting a steady bearing housing
having a bearing in rotational contact with the surface of
a shaft in a vessel, comprising the steps of:
supporting a support ring from the vessel; and
flexing a disc pack that connects the steady
bearing housing to the support ring to permit angular
relative movement between a longitudinal axis of said
housing and a longitudinal axis of said support ring.
According to the present invention, there is also
provided a flexible support assembly for supporting a
steady bearing in rotational contact with surface of a
shaft in a vessel, comprising:
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CA 02401274 2003-05-07
a bearinc:~ housing support ir~g the steady bearing;
a suppoxwt: rirug :~u:,p~~rn:ieci f z r>rcn t.r~ae vessel ,; and
at least: one f:.c.-~x:i.k>:l.ea ~ais~:: pack that solely
connects said hous~.ng to said s~.zppc:>rt: ring.
According to the present rnverrtion, there is also
provided a flexik;~le ~L~.ppr._>r:t: as sernb:i..y fc>r sup~~orting a
steady x:~earing :irv. u.~otat~ic:~ru~L c~:>ntac.~t s~~at~~~ tvrne:~ ~~urf-
ac;e of a
shaft in a vessel, compra.sir~c~:
a bearing housing supporting the steady bearing;
a. support rung su~~p~:,rlcle:c~ fx~::>m t:she vE~s~~el; and
a flexib:i.e disc. k.~r~ck c~ormar~t~~.nc:~ said housing to
said support ring, wherein sa~i.d flexible disc pack includes
a plurality of mounting riole.
Preferably, in E~.ccvordara~e: with. a general
embodiment of the ?resent :i.rx~aentiarl, a.t least oaze flexible
disc pack is provided, which is comprised of a plurality of
thin, flexible disc elememt:~ in a stacked arrangement. The
radial dimens:ioris ~~f the i:rad~.~rv..dua:1 c~:i_:~.c eleme~nte, a.nd the
thickness and nu.mbE~r of disc eTlemer~t.~> can vary dependent on
the dimensions of the shaft arid bear~..ng elements with which
the invention is to be 'used.
Preferably, :in ~:~r~~~ asp~~~c: t of the i:cuvention,
therefore, several disc elements are assembled i.n ;~ stacked
arrangement to produce a "disr~ pack", whirr is incorporated
into the new :f::le:;ible bes~t~:i.:nc~ ~;uppo:r~t.- design. In some
embodiments, a di.s!:;~ pa.c:k i ~.~c m~:~r Lr~c ~c.l ~ ~:f t~hi:~ee~ :i:
rdi.vidual
disc elements, but may ~~ont.ain more based on the
requirements of the bearin~~j cie5ign. '1:'lr~ ciis<: pack can be
mounted to a ric.~id s~.a.ppc:~rt. r ~_anc,~, wh ~-:'ra. ~c.t.-~ as a nma.ns
for
supporting the b~~arinu<,~ ~:>m r...t-ue :i.a,i.~~~::l.:l.~=~r sha t when
'? r-~
f~ w.
CA 02401274 2003-05-07
completely assembled. The support ring can be supported by
an assembly of three or rnor~.:.-~ ~at.rutr~ .
F~refer~abJ..y, aru ,.a.n~c_~,t~~v.ez:, ~~~pc~~:.vt:: of the current
invention, once the d:i.s~~ ~;~~~t~~:.~k :~s .~~~~Y~:m.e:Ly rtaountead to the
rigid support ring , the bear:.ing ho~as:in~~ and other bearing
elements are mounted to tine c~isc~ pack sucrn that the
bearing housing anal other L~e<r~:i..:xg .~:Lern~}nts are c~~pable of
significant deflection arr>und the Verta.r,al axi.;of the
impeller shaft,
There ha:7 thus been ~>ut:L:irrE>:c~, rather broadly, the
more important teat-u:res ~~f tine inver~t:io:n in order that the
detailed description thereof. that f=o:~:i.ows may f>e bet.ter
understood, and in order that the present contribution to
the art may be be~:.ter app.x-ec:z.ated.. There ar°e, c>i: c:ourse,
additional feature:, of t:.r~e i.nve:ot ic.~r. t-.r-~at will be de;~cri.bed
below and which will form t: he sub~ecC m:~tter of the claims
appended hereto.
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In this respect, before explaining at least one embodiment of the invention in
detail,
it is to be understood that the invention is not limited in its application to
the details of
construction and to the arrangements of the components set forth in the
following
description or illustrated in the drawings. The invention is capable of other
embodiments
and of being practiced and carried out in various ways. Also, it is to be
understood that the
phraseology and terminology employed herein, as well as the abstract included
below, are
for the purpose of description and should not be regarded as limiting.
As such, those skilled in the art will appreciate that the conception upon
which this
disclosure is based may readily be utilized as a basis for the designing of
other structures,
methods and systems for carrying out the several purposes of the present
invention. It is
important, therefore, that the claims be regarded as including such equivalent
constructions
insofar as they do not depart from the spirit and scope of the present
invention.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. I illustrates a cross sectional view of an assembled flexible bearing
assembly
using a one piece bearing and a single disc pack.
Fig. 2 illustrates a cross sectional view of an assembled flexible bearing
assembly
using a two piece bearing and two separate disc packs.
Fig. 3 illustrates a plan overhead view of an assembled flexible bearing
assembly of
the current invention.
Fig. 4 illustrates a first contemplated embodiment of a disc element for use
in a
flexible bearing assembly.
Fig. 5 illustrates a second contemplated embodiment of a disc element for use
in a
flexible bearing assembly.
Fig. 6 illustrates a top view of a detachably connectable flexible disc
element.
Fig. 7 illustrates a side cutaway view of a flexible bearing assembly
installed in a
mixing tank.
DETAILED DESCRIPTION OF PREFERRED
EMBODIMENTS OF THE INVENTION
The present invention is a flexible support for a steady bearing, which allows
bearing components to substantially track angular changes in the contact
surfaces of an
impeller shaft when the shaft is subject to angular deflection during
operation. The present
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invention accomplishes this significant improvement by providing at least one
flexible disc
pack, which is comprised of at least one or a plurality of thin, flexible disc
elements in a
stacked arrangement. The individual disc elements most preferably have a
thickness of
approximately 0.020" to 0.040" and are constructed of an alloy material that
provides
sufficient flexibility to the disc elements. However, it is also preferable to
use discs with a
thickness of 0.010" to 0.060". Other thicknesses may also be used. In one
preferred
embodiment, the individual disc elements have a thickness of approximately
0.020" and are
constructed of titanium. The thickness and the radial dimensions of the
individual disc
elements can vary dependent on the dimensions of the shaft and bearing
elements with
which the invention is to be used.
A first embodiment 10 is shown used with a single piece bearing assembly 12
supported on a single disc pack 14 attached to a support ring 16. This
embodiment is
shown e.g., in Fig, l and is explained in greater detail below supporting a
shaft 24.
A second embodiment 30 is shown used with a two piece bearing 32, 34, where an
upper half 32 and a lower half 34 of a bearing assembly are joined by two disc
packs 36, 38
to a common rigid support ring 40. This second design is sometimes preferred
for
application with longer bearing assemblies, typically greater than 20", though
it is also
suitable to use it with bearing assemblies of less than 20". This second
embodiment of the
invention shown e.g. in Fig. 2 includes separate upper and lower disc packs
36, 38 for the
two separate bearing assembly halves 32, 34. However, in some circumstances a
two piece
bearing assembly can be supported using only a single disc pack.
Referring to Fig. 4, a plan view of the top of an individual disc element 50
is
shown, the bottom view of which is substantially the same as the top view. A
plurality of
disc elements 50 are structured to form a disc pack 14, 36 or 38. Although a
disc pack is
shown as an example forming a plurality of individual stacked discs, it may be
preferable
to employ only a single disc, which would then constitute a disc pack. Such
disc element
50 is a ring structure with a center section 52, through which an impeller
shaft can pass. A
first plurality of machined holes 54 are spaced at regular intervals around a
circumference
defined by a circle 56 around the disc element. The first plurality of holes
54 provide a
means by which individual disc elements may be secured together in a disc
pack. The first
plurality of holes 54 further provide a means by which an assembled disc pack
may be
flexibly secured to support ring 16, 40. A second plurality of machined holes
58 are spaced
at regular intervals around the same circle 56 of the disc element, such that
each one of the
second plurality of holes 58 is spaced equidistant between two of the holes
54. The second
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plurality of holes 58 provide a means by which individual disc elements may be
secured
together in a disc pack 14, 36 or 38. The second plurality of holes 58 further
provide a
means by which an assembled disc pack may be flexibly secured to a bearing
housing 12,
32, 34.
Referring to Fig. 5, an embodiment of the disc element is illustrated in top
view, the
bottom view of which is substantially the same as the top view. The disc
element 60 is a
ring structure with a center section 62, through which an impeller shaft can
pass. A first
plurality of machined holes 64 axe spaced at regular intervals around a first,
outer, circle 66
circumscribing the disc element outside a second circle 70. The first
plurality of holes 64
provide a means by which individual disc elements may be secured together in a
disc pack
14, 36 or 38. The first plurality of holes 64 further provide a means by which
an assembled
disc pack may be flexibly secured to a rigid support ring 16, 40. A second
plurality of
machined holes 68 axe spaced at regular intervals around a second, inner,
circle. 70,
circumscribing the disc element. The second plurality of holes 68 provide a
means by
which individual disc elements may be secured together in a disc pack. The
second
plurality of holes 68 further provide a means by which an assembled disc pack
may be
flexibly secured to a bearing housing 12, 32, 34.
The disc pack 14, 36, 38 is mounted to the rigid support ring and the bearing
housing by means of bolts, pins, screws or other appropriate fastening devices
in what may
be a flange type joint. The individual disc elements may be constructed of an
alloy which
imparts sufficient flexibility and corrosion resistance to the disc elements.
Referring to Fig. 1, a preferred embodiment of the present inventive apparatus
and
method is illustrated with a cross section of an assembled flexible steady
support bearing
using a single piece bearing 12. The flexible disc pack 14 is mounted to the
rigid support
ring 16 by fasteners 18 and to bearing housing 12 by means of fasteners 20. A
bearing 22
resides within the bearing housing 12, through which the impeller shaft 24 is
oriented along
an axis of rotation. When the impeller shaft 24 is subj ect to elastic
deflection, the flexible
disc pack 14 flexes, allowing the bearing housing 12 and bearing 22 to track
the contact
surface of the impeller shaft 24. As noted in Fig. 1, in the single piece
bearing
embodiment, the upper and lower ends of the bearing deflect in an angle 0 or
y.
Refernng now to Fig. 3, the assembled flexible steady support bearing assembly
10
of Fig. 1 is shown in plan view. The disc pack 14 is flexibly mounted to a
support ring 16,
by means of fasteners 18. The disc pack 14 is further flexibly mounted to the
bearing
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housing 12, by means of fasteners 20. The mounting of the disc pack 14 to the
support ring
16 and bearing housing 12 as illustrated allows the flexible disc pack 14 to
flex. This in
turn allows the bearing housing to deflect in response to elastic deflection
of the impeller
shaft 24 and thus track the contact surface of the shaft 24. Fig. 1
illustrates angles 0 and y
to wluch the shaft may deflect. These deflections can be accommodated by
flexing of the
disc pack so that the surface of the bearing stays substantially in parallel
contact with the
surface of the shaft. The disc pack also allows for this tracking to occur in
any plane about
the axis of the shaft, e.g. 360°.
Another preferred embodiment of the present inventive apparatus and method is
illustrated in Fig. 2, a cross section of an assembled flexible steady support
bearing using a
two piece bearing. An upper flexible disc pack 36 and lower flexible disc pack
38 axe each
independently flexibly mounted to opposite sides of a support ring 40. The
upper flexible
disc pack 36 is further flexibly mounted to an upper half 32 of a two piece
bearing housing,
wherein resides the upper half 42 of a two piece bearing through which the
impeller shaft
46 is oriented along an axis of rotation. The lower flexible disc pack 38 is
ftirther flexibly
mounted to a Lower half 34 of a two piece bearing housing, wherein resides the
lower half
44 of a two piece bearing through which the impeller shaft 46 is oriented
along an axis of
rotation. When the impeller shaft is subject to elastic deflection, each of
the upper and
lower flexible disc packs 36 and 38 can flex, allowing the each of the upper
and lower
bearing housings 32 and 34 and bearings 42 and 44 to track the impeller shaft
contact
surface. As noted in Fig. 2, in the two piece bearing embodiment, the upper
and lower
ends of the bearing can each deflect in an angle 8 or y together or
independently.
In an alternative preferred embodiment of either the single piece or two piece
bearing embodiments, the rigid support ring, disc elements, bearing housing
and other
bearing elements are separable into substantially equivalent, detachably
connectable
halves, such that they may be removed from the impeller shaft without
disturbing the shaft
itself. Referring to Fig. 6, an embodiment of a separable disc element 80 of
the current
invention is shown. The first half 82 of the disc element 80 has attachment
points 84 and
86 with holes provided through each. The second half 88 of the same disc
element 80 has
corresponding attachment points 90 and 92 with holes provided through each.
The two
halves 82 and 88 are detachably connectable to each other such that a common
bolt, pin or
other fastener passed through both of the holes of attachment points 86 and
92, detachably
locks the two halves together. Similarly, a common bolt, pin or other fastener
passed
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through both of the holes of attachment points 84 and 90 detachably locks the
two halves
together.
It will be noted by one skilled in the art that similar means may be used for
detachably connecting separable halves of rigid support rings, bearing
housings and other
bearing elements. It will further be recognized by one skilled in the art that
well known
means other than the one demonstrated in Fig. 6 may be used to detachably
connect two
halves of the components of the current invention. Thus the present invention
is not
limited to the exact' construction illustrated here.
Fig. 7 illustrates a flexible bearing assembly 10 installed in a vessel 90
supported
by struts 96, with impeller 98 mounted to the shaft 24.
The many features and advantages of the invention are apparent from the
detailed
specification, and thus, it is intended by the appended claims to cover all
such features and
advantages of the invention which fall within the true spirits and scope of
the invention.
Further, since numerous modifications and variations will readily occur to
those skilled in
the art, it is not desired to limit the invention to the exact construction
and operation
illustrated and described, and accordingly, all suitable modifications and
equivalents rnay
be resorted to, falling within the scope of the invention.
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